Feet and footwear (shoes, sandals, socks, etc.) are carriers of multiple contamination agents that are often introduced into interiors of homes, hospitals, schools, and offices from various sources of contamination. Although any portion of the feet/footwear is known to carry/spread contamination, due to contact with contamination from surfaces (e.g. floor), the majority of contamination is carried on the bottom of footwear (or soles of feet).
Most contamination is inert, for example, dirt, sand, dust, leaves, etc. On the contrary, pathogens often lead to the spread of various diseases. A study by Dr. Charles Gerba, microbiologist and professor at the University of Arizona and The Rockport Company made in 2008 confirmed this finding. The study measured germs and microbes collected on footwear. What was found was a large number of bacteria both on the bottom and inside of shoes; averaging 420,000 units of bacteria on the outside of the shoe, and almost 3000 on the inside. The tested footwear picked up 420,000 units of bacteria in just two weeks. The bacteria included Escherichia coli, known to cause intestinal and urinary tract infections, meningitis and diarrheal disease; Klebsiella pneumonia, a common source for wound and bloodstream infections as well as pneumonia; and Serratia ficaria, a rare cause of infections in the respiratory tract and wounds.
Such germs/microbes/pathogens, in addition to other chemicals, are picked up by the feet/shoes in one place and deposited in another, leading to the spread of contamination, possibly to the shoes of other people, etc.
Cleaning/vacuuming of the floor may help reduce exposure to such germs/microbes, but has little or no effect on many. Furthermore, the germs/microbes are not neutralized by vacuuming and pose a health risk when emptying the vacuum cleaner. Using steam cleaners to kill the bacteria was found ineffective in killing germs and bacteria in homes and public places. At the source, the steam has a temperature of around 100 degrees C. but by the time the steam contacts the carpets or the floor, the temperature drops drastically and does not kill many bacteria and the viruses.
Applying chemical products by spraying or spreading on floors or carpets is also partially effective. To kill or disable most pathogens, a very strong chemical is required. As the strength of the chemical increases, so does the risk of potential hazards to health and safety of both the people applying the chemical and to the users of the cleaned surfaces. This is not to mention issues related to allergies. Stronger chemicals also tend to impact/discolor the surfaces on which they are applied. For example, bleach (chorine) is a known effective disinfectant, but bleach applied to one's shoes results in discolored shoes, and, therefore, would not be used by most. Furthermore, bleach (chlorine) does not kill many pathogens that have a protective shell
The feet/shoes cause a major concern, especially in hospital settings. Often, hospitals have isolation wards for people that have highly contagious diseases such as necrotizing fasciitis and Methicillin-resistant Staphylococcus aureus (MRSA). The hospitals attempt to control the spread of such diseases by maintaining a negative air pressure in these wards (so air flows in when a door is opened), constant filtration of the air in the wards, constant germicidal treatment, wearing of disposable outer garments, etc. For the lower extremities, at most, workers use booties to cover their footwear. The use of booties is a weak attempt to solve this problem, especially because the users of such booties use their hands to remove them from their feet.
The lack of diligence in reducing migration of microbes carried on feet/footwear is possibly responsible for an estimated 10% of new cases of disease such as MRSA each year, especially cases of such diseases that are contracted in hospitals. Many times, the hospitals are responsible for fighting these diseases without compensation due to the rationale that they were the source of the disease, resulting in billions of dollars in lost profits.
Beyond hospitals, many areas are also prone to breed germs/microbes and often travel on feet and shoes to homes, offices, etc. For example, public showers in gyms, schools, etc., often breed such microbes and, even after putting on shoes, these microbes get carried on the feet and shoes and often are deposited in homes and offices miles from the source.
Several techniques are known for reducing contamination from feet/shoes, especially for clean room environments in which it is important to limit particle contamination. For example, products used at the entrance to clean rooms include shoe vacuums with Hepa filters, sticky mats, and pressurized air flow to dislodge contaminates, all are only partially effective in removing/containing pathogens, while none actually kill germs.
What is needed is a system that will successfully reduce the number of microbes on one's feet and/or shoes.